There is no single symptom that tells you whether you are sterile. The only way to know for certain is through medical testing, and the specific tests differ for men and women. What most people mean when they search this question is whether they might have a fertility problem, and the answer usually starts with one key benchmark: if you’ve been having regular unprotected sex for 12 months without a pregnancy, that meets the clinical definition of infertility and warrants evaluation.
It’s worth noting that doctors distinguish between infertility and sterility. Infertility means difficulty conceiving, and it’s often treatable. Sterility refers to a permanent inability to produce a child. Most people who struggle to conceive fall into the first category, not the second.
Signs That May Point to a Problem
The main sign of a fertility problem is simply not getting pregnant. Beyond that, the physical clues can be subtle. Women with irregular menstrual cycles or absent periods may have ovulation issues that affect fertility. Cycles that are consistently shorter than 21 days or longer than 35 days, or periods that stop entirely outside of pregnancy, are worth investigating.
For men, there are even fewer outward signs. Testicles that are noticeably smaller than typical adult size, swollen veins in the scrotum (a condition called varicocele), changes in hair growth, or reduced sexual function can all hint at hormonal or structural problems. But many men with fertility issues have no symptoms at all.
When to Get Tested
The American Society for Reproductive Medicine recommends this timeline: women under 35 should seek evaluation after 12 months of trying to conceive without success. Women 35 and older should go after 6 months. Women over 40 may want to start testing sooner, since egg quantity and quality decline more rapidly at that point.
If you already know you have a condition that could affect fertility, such as a history of pelvic infections, undescended testicles, endometriosis, or cancer treatment, there’s no reason to wait. You can request testing at any time.
How Men Are Tested
The primary test for male fertility is a semen analysis. You provide a sample, and a lab evaluates three key measurements: sperm count, motility (how well sperm move), and morphology (the percentage of normally shaped sperm). The current benchmarks consider a total sperm count below 39 million per ejaculate, total motility below 42%, or normal forms below 4% to be below the fifth percentile of fertile men. Falling below one or more of these thresholds doesn’t automatically mean you’re sterile, but it does mean your chances of conceiving naturally are reduced.
If a semen analysis comes back with zero sperm (a result called azoospermia), further testing determines why. It could be a blockage preventing sperm from reaching the ejaculate, or a production problem in the testicles themselves. Some causes are correctable with surgery or hormone treatment. Others are permanent.
At-Home Sperm Tests
Several at-home sperm tests are now available. Some use smartphone cameras to analyze a sample, while others use chemical indicators. Their accuracy varies. The better-performing devices report sensitivity in the high 80s to low 90s percent range and specificity around 75% to 97%, depending on the brand and what they measure. They can give you a rough idea of whether your sperm count or motility is in a normal range, but they don’t replace a full clinical semen analysis. They can’t assess morphology, check for infections, or measure hormone levels. Think of them as a screening tool, not a diagnosis.
How Women Are Tested
Female fertility testing involves several steps, typically starting with blood work and imaging.
- Hormone blood tests check levels of progesterone (which confirms ovulation), estradiol, thyroid-stimulating hormone, and prolactin. Imbalances in any of these can interfere with egg production and maturation.
- Ovarian reserve testing combines a blood test for anti-mullerian hormone (AMH) with a transvaginal ultrasound that counts the small follicles visible on your ovaries. AMH levels between 1.0 and 3.0 ng/mL are considered average. Levels below 1.0 ng/mL indicate low ovarian reserve, and levels around 0.4 ng/mL are severely low. Lower AMH means fewer remaining eggs, though it doesn’t tell you anything about egg quality.
- Hysterosalpingogram (HSG) is an imaging test where dye is injected into the uterus and X-rays track whether it flows freely through both fallopian tubes. If the dye stops short, that suggests a blockage. Blocked tubes prevent egg and sperm from meeting, and tubal problems account for a significant share of female infertility. If a blockage is found, doctors may administer medication to rule out a temporary muscle spasm before confirming a true obstruction.
- Ultrasound and sonohysterogram let your provider look at the uterus and ovaries directly, checking for fibroids, cysts, polyps, or structural abnormalities that could interfere with implantation.
No single test gives the full picture. A provider typically works through these in sequence, starting with less invasive options and moving to more detailed imaging if needed.
Conditions That Cause Permanent Sterility
True sterility, where conception is biologically impossible, is relatively rare. It typically results from genetic conditions or the complete absence of reproductive cells.
In women, Turner syndrome (where one X chromosome is missing or incomplete) can result in ovaries that contain virtually no eggs. Women with a full 45,X karyotype have extremely low chances of eggs being present at all. In men, a condition called XX male syndrome means no sperm can be retrieved, even with surgical extraction from the testicle. Certain deletions on the Y chromosome (specifically in the AZFa, AZFb, or AZFbc regions) also result in near-zero chances of finding viable sperm through biopsy.
Klinefelter syndrome, where men carry an extra X chromosome, causes severely reduced or absent sperm production, though in some cases sperm can still be surgically retrieved. The distinction matters: some genetic conditions leave a small window for assisted reproduction, while others close it entirely.
After a Vasectomy or Tubal Ligation
If you’ve had a vasectomy, sterility isn’t immediate. It takes time for remaining sperm to clear from the reproductive tract. Surgeons typically order a follow-up semen analysis between 8 and 16 weeks after the procedure, and many guidelines recommend waiting until you’ve had at least 20 ejaculations. The vasectomy is considered successful when a sample shows no sperm, or fewer than 100,000 non-motile sperm per milliliter. If any motile (swimming) sperm are still detected at the six-month mark, the vasectomy is considered a failure, and a repeat procedure may be needed.
Tubal ligation in women is similarly effective but not absolute. Confirmation is less straightforward than a semen analysis, and while failure rates are very low, they’re not zero. If you’ve had your tubes tied and experience signs of pregnancy, testing is appropriate.
What Test Results Actually Tell You
Fertility exists on a spectrum. A low sperm count doesn’t mean you can never conceive, and a normal AMH level doesn’t guarantee you will. Test results help quantify your chances and guide treatment decisions, but they rarely deliver a simple yes-or-no answer. The exception is when testing reveals a complete absence of eggs or sperm, or a genetic condition that makes natural conception impossible.
For most people who receive concerning results, the news is that conception will be harder, not that it’s out of reach. Treatments ranging from medication that stimulates ovulation to procedures like IVF can overcome many of the barriers that testing identifies. The value of getting tested early is that it gives you information while you still have time to act on it, particularly for women, whose ovarian reserve declines steadily with age.